The myth that birds rip it right after a rain has been perpetuated since I was a pup chasing these things. Sure they can and do sometimes get wild after a rain, but there are a million variables. Is it a warm rain or cold rain? Is it a massive cold front or just a warm front with moisture? What's the barometric pressure do post rain, rise or fall? Are the clouds going to linger or stay? What breeding phase are the birds in? All of those play a huge role in post rain hunts.
This particular system for us will be a cold rain, over cold dirt, with high winds and possible winter precip on the back end, it's a big nasty low. My experience with these is that the birds are dead quiet afterwards.
Also, the way they are so grouped up will have a bigger impact, gobblers gobble to attract hens, well they will be staring at their hens and won't have the dawn rush testosterone which makes them gobble on the roost. Therefore again, probably going to be quiet.
With all that said, they live in the weather and will be going about their day as normal. The field thing is partly true, but with no leaves the open woods are fairly field like and the birds will stay in the woods as much as the open ground, so don't feel like a field is mandatory because its not.
Hunting in the rain is no fun,period. However it's spring and part of it, I've killed them in every form of precipitation so it's only a minor inconvenience. I will be on a mountain side in mature hardwoods come daylight, if he's there I'll kill him there if he drops to open ground we will do battle in the open. Makes no difference and I learned a longtime ago predicting where turkeys are going to be is a great way to go home empty handed